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Flarm reporting my own ADSB Out



 
 
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  #11  
Old March 21st 18, 07:46 PM posted to rec.aviation.soaring
Darryl Ramm
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Default Flarm reporting my own ADSB Out

On Wednesday, March 21, 2018 at 11:14:28 AM UTC-7, Dirk_PW wrote:
Question... Has anyone with a FLARM actually flown close enough to a glider that is outputting both ADS-B and FLARM and verified that only one aircraft appears on their display? The glider would have to be in range of the FLARM to ensure that both signals are hitting the front end of the FLARM.


Yes PowerFLARM 1090ES In and FLARM deduplication works. Why the question? If it's not working the likely suspect is the FLARM or transponder have mismatching ICAO addresses.
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  #12  
Old March 22nd 18, 12:34 AM posted to rec.aviation.soaring
Dirk_PW[_2_]
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Default Flarm reporting my own ADSB Out

My question was largely curiosity. I see validation about 'own ship' duplication but nothing about 'off board' duplication when a different receiver is sensing two separate signals with the same ICAO address. Good to know it is working. With all this great info that has been shared I think I'm going to move forward with a TABS ADS-B install. Thanks for all the time spent researching and sharing this info.

BTW, it begs the question whether it would make sense to have the ability to turn off the FLARM xmtr if you are already outputting ADS-B out, and everyone you fly with has at least a PowerFlarm and can sense the 1090ES signal.. It would cut down on unneeded transmission (and reduce battery power consumption). Thoughts there?
  #13  
Old March 22nd 18, 01:56 AM posted to rec.aviation.soaring
[email protected]
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Default Flarm reporting my own ADSB Out

On Wednesday, March 21, 2018 at 12:46:21 PM UTC-7, Darryl Ramm wrote:
Yes PowerFLARM 1090ES In and FLARM deduplication works. Why the question?
If it's not working the likely suspect is the FLARM or transponder have mismatching ICAO addresses.


It's still spotty deduplicating Mode S and FLARM. A friend and I have flown together several times and the false alerts can get annoying. We both have LX9000 and Trig transponders. We've gone over and over the configs and have been in touch with FLARM and LXnav. The answer is that they're still working on such issues and future firmware may get better.

We flew together last Sunday, and both still get occasional PCAS warnings complete with the contest number while at the same time seeing the FLARM target. I also get self alerts every 20-30 minutes or so.

5Z
  #14  
Old March 22nd 18, 02:14 AM posted to rec.aviation.soaring
Ramy[_2_]
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Default Flarm reporting my own ADSB Out

I am not aware of mode S and flarm deduplication so what you see is expected behavior. The problem is in the LX9000 side as I pointed out in another thread. They promised to have an option to turn off PCAS collision alarm from mode c/s which is what you need. You will still get timely alerts but not annoying alarm if they implement it correctly.
ADSB is a different case. Flarm suppose to ignore the ADSB signal when receiving flarm signal. I sure hope it is working as expected. If not I will find out soon that I am driving my buddies crazy when thermaling together.

Ramy
  #15  
Old March 22nd 18, 03:31 AM posted to rec.aviation.soaring
Darryl Ramm
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Default Flarm reporting my own ADSB Out

On Wednesday, March 21, 2018 at 7:15:00 PM UTC-7, Ramy wrote:
I am not aware of mode S and flarm deduplication so what you see is expected behavior. The problem is in the LX9000 side as I pointed out in another thread. They promised to have an option to turn off PCAS collision alarm from mode c/s which is what you need. You will still get timely alerts but not annoying alarm if they implement it correctly.
ADSB is a different case. Flarm suppose to ignore the ADSB signal when receiving flarm signal. I sure hope it is working as expected. If not I will find out soon that I am driving my buddies crazy when thermaling together.

Ramy


Mode S PCAS is _supposed_ to deduplicate in the PowerFLARM, a Mode S PCAS alert detects the target aircraft's ICAO address, if the PowerFLARM sees the same ICAO address via ADS-B Out or FLARM it should ignore the PCAS. As I've pointed out before, the main issue with spurious *PCAS* alerts is you can't stop Mode S transponders being interrogated by legacy Mode C (not Mode S capable) interrogators and then your transponder has to reply with an old style Mode C reply with no Mode S ICAO address. And then your PowerFLARM will have a lot harder job of trying to guess if it needs to deduplicate that PCAS traffic vs 1090ES or FLARM warnings. And sure there are lots of room here for things to still not happen properly, including between the PowerFLARM and display (e.g. timing windows between when different signals are received).

The classic example of a device that causes those Mode C interrogations is the Ryan TCAD interrogators still flying around in some GA aircraft, they were Mode C not Mode S capable and an aircraft equipped with one of those within several tens of miles of you may cause these issues with non-deduplicated targets and self-targets. TCAS I and II systems are Mode S interrogators so should not do this.

This discussion has already got to confusing levels. Are we talking FLARM actual warnings or LXNav handling of them. 1090ES traffic or PCAS etc. I've gotten lost. And really belongs in a discussion with the appropriate vendors, as we all see to be agreeing on.
 




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